This invention relates to steam turbines and more particularly to the closing blade locking system for a circular array of curved root side entry rotating blades. Curved root side entry blades are installed in curved slots in the rotor disc one at a time and as shown in U.S. Pat. No. 3,986,793 have a pin which is installed in a notch in the platform of the blade and a groove in the disc to lock the blade in place in the disc. The next blade to be installed captures the pin preventing it from coming free. Due to the curved root, the last few blades to be installed in the array, the closing blades, cannot receive the pin which fits into the notch and groove as they must be installed in unison and often from different sides of the disc, thus requiring a special locking system.